<!DOCTYPE html>
<html lang="en" dir="ltr" class="client-nojs">
<head>
<title>Extending the namespace std - cppreference.com</title>
<meta charset="UTF-8">
<meta name="generator" content="MediaWiki 1.21.2">
<link rel="shortcut icon" href="../../../common/favicon.ico">
<link rel="stylesheet" href="../../../common/ext.css">
<meta name="ResourceLoaderDynamicStyles" content="">
<link rel="stylesheet" href="../../../common/site_modules.css">
<style>a:lang(ar),a:lang(ckb),a:lang(fa),a:lang(kk-arab),a:lang(mzn),a:lang(ps),a:lang(ur){text-decoration:none}#toc{display:none}.editsection{display:none}
/* cache key: mwiki1-mwiki_en_:resourceloader:filter:minify-css:7:472787eddcf4605d11de8c7ef047234f */</style>

<script src="../../../common/startup_scripts.js"></script>
<script>if(window.mw){
mw.config.set({"wgCanonicalNamespace":"","wgCanonicalSpecialPageName":false,"wgNamespaceNumber":0,"wgPageName":"cpp/language/extending_std","wgTitle":"cpp/language/extending std","wgCurRevisionId":136879,"wgArticleId":13097,"wgIsArticle":true,"wgAction":"view","wgUserName":null,"wgUserGroups":["*"],"wgCategories":["Todo with reason","Pages with unreviewed LWG DR marker"],"wgBreakFrames":false,"wgPageContentLanguage":"en","wgSeparatorTransformTable":["",""],"wgDigitTransformTable":["",""],"wgDefaultDateFormat":"dmy","wgMonthNames":["","January","February","March","April","May","June","July","August","September","October","November","December"],"wgMonthNamesShort":["","Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"],"wgRelevantPageName":"cpp/language/extending_std","wgRestrictionEdit":[],"wgRestrictionMove":[]});
}</script><script>if(window.mw){
mw.loader.implement("user.options",function(){mw.user.options.set({"ccmeonemails":0,"cols":80,"date":"default","diffonly":0,"disablemail":0,"disablesuggest":0,"editfont":"default","editondblclick":0,"editsection":0,"editsectiononrightclick":0,"enotifminoredits":0,"enotifrevealaddr":0,"enotifusertalkpages":1,"enotifwatchlistpages":0,"extendwatchlist":0,"externaldiff":0,"externaleditor":0,"fancysig":0,"forceeditsummary":0,"gender":"unknown","hideminor":0,"hidepatrolled":0,"imagesize":2,"justify":0,"math":1,"minordefault":0,"newpageshidepatrolled":0,"nocache":0,"noconvertlink":0,"norollbackdiff":0,"numberheadings":0,"previewonfirst":0,"previewontop":1,"quickbar":5,"rcdays":7,"rclimit":50,"rememberpassword":0,"rows":25,"searchlimit":20,"showhiddencats":0,"showjumplinks":1,"shownumberswatching":1,"showtoc":0,"showtoolbar":1,"skin":"cppreference2","stubthreshold":0,"thumbsize":2,"underline":2,"uselivepreview":0,"usenewrc":0,"watchcreations":0,"watchdefault":0,"watchdeletion":0,
"watchlistdays":3,"watchlisthideanons":0,"watchlisthidebots":0,"watchlisthideliu":0,"watchlisthideminor":0,"watchlisthideown":0,"watchlisthidepatrolled":0,"watchmoves":0,"wllimit":250,"variant":"en","language":"en","searchNs0":true,"searchNs1":false,"searchNs2":false,"searchNs3":false,"searchNs4":false,"searchNs5":false,"searchNs6":false,"searchNs7":false,"searchNs8":false,"searchNs9":false,"searchNs10":false,"searchNs11":false,"searchNs12":false,"searchNs13":false,"searchNs14":false,"searchNs15":false,"gadget-ColiruCompiler":1,"gadget-MathJax":1});;},{},{});mw.loader.implement("user.tokens",function(){mw.user.tokens.set({"editToken":"+\\","patrolToken":false,"watchToken":false});;},{},{});
/* cache key: mwiki1-mwiki_en_:resourceloader:filter:minify-js:7:9f05c6caceb9bb1a482b6cebd4c5a330 */
}</script>
<script>if(window.mw){
mw.loader.load(["mediawiki.page.startup","mediawiki.legacy.wikibits","mediawiki.legacy.ajax"]);
}</script>
<style type="text/css">/*<![CDATA[*/
.source-cpp {line-height: normal;}
.source-cpp li, .source-cpp pre {
	line-height: normal; border: 0px none white;
}
/**
 * GeSHi Dynamically Generated Stylesheet
 * --------------------------------------
 * Dynamically generated stylesheet for cpp
 * CSS class: source-cpp, CSS id: 
 * GeSHi (C) 2004 - 2007 Nigel McNie, 2007 - 2008 Benny Baumann
 * (http://qbnz.com/highlighter/ and http://geshi.org/)
 * --------------------------------------
 */
.cpp.source-cpp .de1, .cpp.source-cpp .de2 {font: normal normal 1em/1.2em monospace; margin:0; padding:0; background:none; vertical-align:top;}
.cpp.source-cpp  {font-family:monospace;}
.cpp.source-cpp .imp {font-weight: bold; color: red;}
.cpp.source-cpp li, .cpp.source-cpp .li1 {font-weight: normal; vertical-align:top;}
.cpp.source-cpp .ln {width:1px;text-align:right;margin:0;padding:0 2px;vertical-align:top;}
.cpp.source-cpp .li2 {font-weight: bold; vertical-align:top;}
.cpp.source-cpp .kw1 {color: #0000dd;}
.cpp.source-cpp .kw2 {color: #0000ff;}
.cpp.source-cpp .kw3 {color: #0000dd;}
.cpp.source-cpp .kw4 {color: #0000ff;}
.cpp.source-cpp .co1 {color: #909090;}
.cpp.source-cpp .co2 {color: #339900;}
.cpp.source-cpp .coMULTI {color: #ff0000; font-style: italic;}
.cpp.source-cpp .es0 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es1 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es2 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es3 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es4 {color: #008000; font-weight: bold;}
.cpp.source-cpp .es5 {color: #008000; font-weight: bold;}
.cpp.source-cpp .br0 {color: #008000;}
.cpp.source-cpp .sy0 {color: #008000;}
.cpp.source-cpp .sy1 {color: #000080;}
.cpp.source-cpp .sy2 {color: #000040;}
.cpp.source-cpp .sy3 {color: #000040;}
.cpp.source-cpp .sy4 {color: #008080;}
.cpp.source-cpp .st0 {color: #008000;}
.cpp.source-cpp .nu0 {color: #000080;}
.cpp.source-cpp .nu6 {color: #000080;}
.cpp.source-cpp .nu8 {color: #000080;}
.cpp.source-cpp .nu12 {color: #000080;}
.cpp.source-cpp .nu16 {color:#000080;}
.cpp.source-cpp .nu17 {color:#000080;}
.cpp.source-cpp .nu18 {color:#000080;}
.cpp.source-cpp .nu19 {color:#000080;}
.cpp.source-cpp .ln-xtra, .cpp.source-cpp li.ln-xtra, .cpp.source-cpp div.ln-xtra {background-color: #ffc;}
.cpp.source-cpp span.xtra { display:block; }

/*]]>*/
</style><!--[if lt IE 7]><style type="text/css">body{behavior:url("/mwiki/skins/cppreference2/csshover.min.htc")}</style><![endif]--></head>
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_language_extending_std skin-cppreference2 action-view cpp-navbar">
        <!-- header -->
        <!-- /header -->
        <!-- content -->
<div id="cpp-content-base">
            <div id="content">
                <a id="top"></a>
                <div id="mw-js-message" style="display:none;"></div>
                                <!-- firstHeading -->
<h1 id="firstHeading" class="firstHeading">Extending the namespace <code>std</code></h1>
                <!-- /firstHeading -->
                <!-- bodyContent -->
                <div id="bodyContent">
                                        <!-- tagline -->
                    <div id="siteSub">From cppreference.com</div>
                    <!-- /tagline -->
                                        <!-- subtitle -->
                    <div id="contentSub"><span class="subpages">&lt; <a href="../../cpp.html" title="cpp">cpp</a>‎ | <a href="../language.html" title="cpp/language">language</a></span></div>
                    <!-- /subtitle -->
                                                            <!-- bodycontent -->
                    <div id="mw-content-text" lang="en" dir="ltr" class="mw-content-ltr"><div class="t-navbar" style=""><div class="t-navbar-sep"> </div><div class="t-navbar-head"><a href="../../cpp.html" title="cpp"> C++</a><div class="t-navbar-menu"><div><div><table class="t-nv-begin" cellpadding="0" style="line-height:1.1em;">
<tr class="t-nv"><td colspan="5"> <a href="../compiler_support.html" title="cpp/compiler support"> Compiler support</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../freestanding.html" title="cpp/freestanding"> Freestanding and hosted</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../language.html" title="cpp/language"> Language</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../header.html" title="cpp/header"> Standard library headers</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../named_req.html" title="cpp/named req"> Named requirements </a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../feature_test.html" title="cpp/feature test"> Feature test macros </a> <span class="t-mark-rev t-since-cxx20">(C++20)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../utility.html#Language_support" title="cpp/utility"> Language support library</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../concepts.html" title="cpp/concepts"> Concepts library</a> <span class="t-mark-rev t-since-cxx20">(C++20)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../meta.html" title="cpp/meta"> Metaprogramming library</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../error.html" title="cpp/error"> Diagnostics library</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../utility.html" title="cpp/utility"> General utilities library</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../string.html" title="cpp/string"> Strings library</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../container.html" title="cpp/container"> Containers library</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../iterator.html" title="cpp/iterator"> Iterators library</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../ranges.html" title="cpp/ranges"> Ranges library</a> <span class="t-mark-rev t-since-cxx20">(C++20)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../algorithm.html" title="cpp/algorithm"> Algorithms library</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../numeric.html" title="cpp/numeric"> Numerics library</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../locale.html" title="cpp/locale"> Localizations library</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../io.html" title="cpp/io"> Input/output library</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../filesystem.html" title="cpp/filesystem"> Filesystem library</a> <span class="t-mark-rev t-since-cxx17">(C++17)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../regex.html" title="cpp/regex"> Regular expressions library</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../thread.html" title="cpp/thread"> Concurrency support library</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../experimental.html" title="cpp/experimental"> Technical specifications</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../symbol_index.html" title="cpp/symbol index"> Symbols index</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../links/libs.html" title="cpp/links/libs"> External libraries</a> </td></tr>
</table></div><div></div></div></div></div><div class="t-navbar-sep"> </div><div class="t-navbar-head"><a href="../language.html" title="cpp/language"> C++ language</a><div class="t-navbar-menu"><div><div style="display:inline-block">
<div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv-h1"><td colspan="5"> General topics</td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="../preprocessor.html" title="cpp/preprocessor"> Preprocessor</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="../comments.html" title="cpp/comment"> Comments</a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="../keywords.html" title="cpp/keyword"> Keywords</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="escape.html" title="cpp/language/escape"> Escape sequences</a></td></tr>
</table></div></td></tr>
<tr class="t-nv-h1"><td colspan="5"> <a href="statements.html" title="cpp/language/statements"> Flow control</a></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Conditional execution statements</td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="if.html" title="cpp/language/if"><tt>if</tt></a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="switch.html" title="cpp/language/switch"><tt>switch</tt></a></td></tr>
</table></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Iteration statements (loops)</td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="for.html" title="cpp/language/for"><tt>for</tt></a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="range-for.html" title="cpp/language/range-for"> range-<code>for</code></a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="while.html" title="cpp/language/while"><tt>while</tt></a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="do.html" title="cpp/language/do"> <code>do-while</code></a></td></tr>
</table></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Jump statements </td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="continue.html" title="cpp/language/continue"><tt>continue</tt></a> - <a href="break.html" title="cpp/language/break"><tt>break</tt></a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="goto.html" title="cpp/language/goto"><tt>goto</tt></a> - <a href="return.html" title="cpp/language/return"><tt>return</tt></a></td></tr>
</table></div></td></tr>
<tr class="t-nv-h1"><td colspan="5"> <a href="functions.html" title="cpp/language/functions"> Functions</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="function.html" title="cpp/language/function"> Function declaration</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="lambda.html" title="cpp/language/lambda"> Lambda function expression</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="inline.html" title="cpp/language/inline"> <code>inline</code> specifier</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="except_spec.html" title="cpp/language/except spec"> Dynamic exception specifications</a> <span class="t-mark-rev t-until-cxx20">(until C++20)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="noexcept_spec.html" title="cpp/language/noexcept spec"> <code>noexcept</code> specifier</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv-h1"><td colspan="5"> Exceptions</td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="throw.html" title="cpp/language/throw"> <code>throw</code>-expression</a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="try_catch.html" title="cpp/language/try catch"> <code>try</code>-<code>catch</code> block</a></td></tr>
</table></div></td></tr>
<tr class="t-nv-h1"><td colspan="5"> Namespaces</td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="namespace.html" title="cpp/language/namespace"> Namespace declaration</a>  </td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="namespace_alias.html" title="cpp/language/namespace alias"> Namespace aliases</a></td></tr>
</table></div></td></tr>
<tr class="t-nv-h1"><td colspan="5"> Types</td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="types.html" title="cpp/language/types"> Fundamental types</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="enum_class.html" title="cpp/language/enum"> Enumeration types</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="function.html" title="cpp/language/function"> Function types</a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="class.html" title="cpp/language/class"> Class/struct types</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="union.html" title="cpp/language/union"> Union types</a></td></tr>
</table></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Specifiers</td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="decltype.html" title="cpp/language/decltype"><tt>decltype</tt></a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="auto.html" title="cpp/language/auto"><tt>auto</tt></a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="alignas.html" title="cpp/language/alignas"><tt>alignas</tt></a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="cv.html" title="cpp/language/cv"> <code>const</code>/<code>volatile</code></a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="constexpr.html" title="cpp/language/constexpr"><tt>constexpr</tt></a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
</table></div></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="storage_duration.html" title="cpp/language/storage duration"> Storage duration specifiers</a></td></tr>
<tr class="t-nv-h2"><td colspan="5"> <a href="initialization.html" title="cpp/language/initialization"> Initialization</a></td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="default_initialization.html" title="cpp/language/default initialization"> Default initialization</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="value_initialization.html" title="cpp/language/value initialization"> Value initialization</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="zero_initialization.html" title="cpp/language/zero initialization"> Zero initialization</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="copy_initialization.html" title="cpp/language/copy initialization"> Copy initialization</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="direct_initialization.html" title="cpp/language/direct initialization"> Direct initialization</a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="aggregate_initialization.html" title="cpp/language/aggregate initialization"> Aggregate initialization</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="list_initialization.html" title="cpp/language/list initialization"> List initialization</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="constant_initialization.html" title="cpp/language/constant initialization"> Constant initialization</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="reference_initialization.html" title="cpp/language/reference initialization"> Reference initialization</a></td></tr>
</table></div></td></tr>
</table></div>
</div>
<div style="display:inline-block">
<div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv-h1"><td colspan="5"> <a href="expressions.html" title="cpp/language/expressions"> Expressions</a></td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="value_category.html" title="cpp/language/value category"> Value categories</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="eval_order.html" title="cpp/language/eval order"> Order of evaluation</a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="operators.html" title="cpp/language/operators"> Operators</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="operator_precedence.html" title="cpp/language/operator precedence"> Operator precedence</a></td></tr>
</table></div></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="operator_alternative.html" title="cpp/language/operator alternative"> Alternative representations</a></td></tr>
<tr class="t-nv-h2"><td colspan="5"> <a href="expressions.html#Literals" title="cpp/language/expressions"> Literals</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="bool_literal.html" title="cpp/language/bool literal"> Boolean</a> - <a href="integer_literal.html" title="cpp/language/integer literal"> Integer</a> - <a href="floating_literal.html" title="cpp/language/floating literal"> Floating-point</a></td></tr>   
<tr class="t-nv"><td colspan="5"> <a href="character_literal.html" title="cpp/language/character literal"> Character</a> - <a href="string_literal.html" title="cpp/language/string literal"> String</a> - <a href="nullptr.html" title="cpp/language/nullptr"><tt>nullptr</tt></a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr> 
<tr class="t-nv"><td colspan="5"> <a href="user_literal.html" title="cpp/language/user literal"> User-defined</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv-h1"><td colspan="5"> Utilities</td></tr>
<tr class="t-nv"><td colspan="5"> <a href="attributes.html" title="cpp/language/attributes"> Attributes</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Types</td></tr>
<tr class="t-nv"><td colspan="5"> <a href="typedef.html" title="cpp/language/typedef"> <code>typedef</code> declaration</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="type_alias.html" title="cpp/language/type alias"> Type alias declaration</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Casts</td></tr>
<tr class="t-nv"><td colspan="5"> <a href="implicit_cast.html" title="cpp/language/implicit conversion"> Implicit conversions</a> - <a href="explicit_cast.html" title="cpp/language/explicit cast"> Explicit conversions</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="static_cast.html" title="cpp/language/static cast"><tt>static_cast</tt></a> - <a href="dynamic_cast.html" title="cpp/language/dynamic cast"><tt>dynamic_cast</tt></a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="const_cast.html" title="cpp/language/const cast"><tt>const_cast</tt></a> - <a href="reinterpret_cast.html" title="cpp/language/reinterpret cast"><tt>reinterpret_cast</tt></a></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Memory allocation</td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="new.html" title="cpp/language/new"> <code>new</code> expression</a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="delete.html" title="cpp/language/delete"> <code>delete</code> expression</a></td></tr>
</table></div></td></tr>
<tr class="t-nv-h1"><td colspan="5"> <a href="classes.html" title="cpp/language/classes"> Classes</a></td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="class.html" title="cpp/language/class"> Class declaration</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="initializer_list.html" title="cpp/language/constructor"> Constructors</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="this.html" title="cpp/language/this"> <code>this</code> pointer</a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="access.html" title="cpp/language/access"> Access specifiers</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="friend.html" title="cpp/language/friend"> <code>friend</code> specifier</a></td></tr>
</table></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Class-specific function properties</td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="virtual.html" title="cpp/language/virtual"> Virtual function</a> </td></tr>
<tr class="t-nv"><td colspan="5"> <a href="override.html" title="cpp/language/override"> <code>override</code> specifier</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="final.html" title="cpp/language/final"> <code>final</code> specifier</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="explicit.html" title="cpp/language/explicit"><tt>explicit</tt></a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="static.html" title="cpp/language/static"><tt>static</tt></a> </td></tr>
</table></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Special member functions</td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="default_constructor.html" title="cpp/language/default constructor"> Default constructor</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="copy_constructor.html" title="cpp/language/copy constructor"> Copy constructor</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="move_constructor.html" title="cpp/language/move constructor"> Move constructor</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="as_operator.html" title="cpp/language/as operator" class="mw-redirect"> Copy assignment</a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="move_operator.html" title="cpp/language/move operator" class="mw-redirect"> Move assignment</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="destructor.html" title="cpp/language/destructor"> Destructor</a></td></tr>
</table></div></td></tr>
<tr class="t-nv-h1"><td colspan="5"><a href="templates.html" title="cpp/language/templates"> Templates</a> </td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="class_template.html" title="cpp/language/class template"> Class template </a></td></tr>
<tr class="t-nv"><td colspan="5"> <a href="function_template.html" title="cpp/language/function template"> Function template </a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="template_specialization.html" title="cpp/language/template specialization"> Template specialization</a></td></tr>   
<tr class="t-nv"><td colspan="5"> <a href="parameter_pack.html" title="cpp/language/parameter pack"> Parameter packs</a> <span class="t-mark-rev t-since-cxx11">(C++11)</span></td></tr>
</table></div></td></tr>
<tr class="t-nv-h1"><td colspan="5"> Miscellaneous </td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="asm.html" title="cpp/language/asm"> Inline assembly</a></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"> <a href="history.html" title="cpp/language/history"> History of C++</a></td></tr>
</table></div></td></tr>
</table></div>
</div><div></div></div></div></div><div class="t-navbar-sep"> </div></div>
<h3><span class="mw-headline" id="Adding_declarations_to_std">Adding declarations to <code>std</code></span></h3>
<p>It is undefined behavior to add declarations or definitions to <code>namespace std</code> or to any namespace nested within <code>std</code>, with a few exceptions noted below.
</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="cpp source-cpp"><pre class="de1"><span class="co2">#include &lt;utility&gt;</span>
 
<span class="kw1">namespace</span> std
<span class="br0">{</span>
    <span class="co1">// a function definition added to namespace std: undefined behavior</span>
    pair<span class="sy1">&lt;</span><span class="kw4">int</span>, <span class="kw4">int</span><span class="sy1">&gt;</span> operator<span class="sy2">+</span><span class="br0">(</span>pair<span class="sy1">&lt;</span><span class="kw4">int</span>, <span class="kw4">int</span><span class="sy1">&gt;</span> a, pair<span class="sy1">&lt;</span><span class="kw4">int</span>, <span class="kw4">int</span><span class="sy1">&gt;</span> b<span class="br0">)</span>
    <span class="br0">{</span>
        <span class="kw1">return</span> <span class="br0">{</span>a.<span class="me1">first</span> <span class="sy2">+</span> b.<span class="me1">first</span>, a.<span class="me1">second</span> <span class="sy2">+</span> b.<span class="me1">second</span><span class="br0">}</span><span class="sy4">;</span>
    <span class="br0">}</span>
<span class="br0">}</span></pre></div></div>
<h3><span class="mw-headline" id="Adding_template_specializations">Adding template specializations</span></h3>
<h4><span class="mw-headline" id="Class_templates">Class templates</span></h4>
<p>It is allowed to add template specializations for any standard library class template to the namespace <code>std</code> only if the declaration depends on at least one program-defined type and the specialization satisfies all requirements for the original template, except where such specializations are prohibited.
</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="cpp source-cpp"><pre class="de1"><span class="co1">// Get the declaration of the primary std::hash template.</span>
<span class="co1">// We are not permitted to declare it ourselves.</span>
<span class="co1">// &lt;typeindex&gt; is guaranteed to provide such a declaration, </span>
<span class="co1">// and is much cheaper to include than &lt;functional&gt;.</span>
 
<span class="co2">#include &lt;typeindex&gt; </span>
 
<span class="co1">// Specialize std::hash so that MyType can be used as a key in </span>
<span class="co1">// std::unordered_set and std::unordered_map.  Opening namespace</span>
<span class="co1">// std can accidentally introduce undefined behavior, and is not</span>
<span class="co1">// necessary for specializing class templates.</span>
<span class="kw1">template</span><span class="sy1">&lt;&gt;</span>
<span class="kw1">struct</span> <a href="../utility/hash.html"><span class="kw1127">std::<span class="me2">hash</span></span></a><span class="sy1">&lt;</span>MyType<span class="sy1">&gt;</span>
<span class="br0">{</span>
    <a href="../types/size_t.html"><span class="kw106">std::<span class="me2">size_t</span></span></a> operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span><span class="kw4">const</span> MyType<span class="sy3">&amp;</span> t<span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span> <span class="kw1">return</span> t.<span class="me1">hash</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span> <span class="br0">}</span>
<span class="br0">}</span><span class="sy4">;</span></pre></div></div>
<ul><li> Specializing the template <span class="t-lc"><a href="../numeric/complex.html" title="cpp/numeric/complex">std::complex</a></span> for any type other than float, double, and long double is unspecified.
</li></ul>
<ul><li> Specializations of <span class="t-lc"><a href="../types/numeric_limits.html" title="cpp/types/numeric limits">std::numeric_limits</a></span> must define all members declared <span class="t-rev-inl t-until-cxx11"><span><code>static const</code></span> <span><span class="t-mark-rev t-until-cxx11">(until C++11)</span></span></span><span class="t-rev-inl t-since-cxx11"><span><code>static constexpr</code></span> <span><span class="t-mark-rev t-since-cxx11">(since C++11)</span></span></span> in the primary template, in such a way that they are usable as <a href="constant_expression.html" title="cpp/language/constant expression">integral constant expressions</a>.
</li></ul>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx11"><td>
<ul><li> None of the templates defined in <a href="../header/type_traits.html" title="cpp/header/type traits"><tt>&lt;type_traits&gt;</tt></a> may be specialized for a program-defined type, except for <span class="t-lc"><a href="../types/common_type.html" title="cpp/types/common type">std::common_type</a></span><span class="t-rev-inl t-since-cxx20"><span> and <a href="../types/common_reference.html#Helper_types" title="cpp/types/common reference"><tt>std::basic_common_reference</tt></a></span> <span><span class="t-mark-rev t-since-cxx20">(since C++20)</span></span></span>. This includes the <a href="../types.html" title="cpp/types">type traits</a> and the class template <span class="t-lc"><a href="../types/integral_constant.html" title="cpp/types/integral constant">std::integral_constant</a></span>.
</li></ul>
<ul><li> Specializations of <span class="t-lc"><a href="../utility/hash.html" title="cpp/utility/hash">std::hash</a></span> for program-defined types must satisfy <a href="../named_req/Hash.html" title="cpp/named req/Hash"><span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">Hash</span></a> requirements.
</li></ul>
<ul><li> Specializations of <span class="t-lc"><a href="../atomic/atomic.html" title="cpp/atomic/atomic">std::atomic</a></span> must have a deleted copy constructor, a deleted copy assignment operator, and a constexpr value constructor.
</li></ul>
<ul><li> Specializations of <span class="t-lc"><a href="../memory/shared_ptr.html" title="cpp/memory/shared ptr">std::shared_ptr</a></span> and <span class="t-lc"><a href="../memory/weak_ptr.html" title="cpp/memory/weak ptr">std::weak_ptr</a></span> must be <a href="../named_req/CopyConstructible.html" title="cpp/named req/CopyConstructible"><span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">CopyConstructible</span></a> and <a href="../named_req/CopyAssignable.html" title="cpp/named req/CopyAssignable"><span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">CopyAssignable</span></a>. In addition, specializations of <span class="t-lc"><a href="../memory/shared_ptr.html" title="cpp/memory/shared ptr">std::shared_ptr</a></span> must be <a href="../named_req/LessThanComparable.html" title="cpp/named req/LessThanComparable"><span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">LessThanComparable</span></a>, and convertible to <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span></span></span>.
</li></ul>
<ul><li> Specializations of <span class="t-lc"><a href="../iterator/istreambuf_iterator.html" title="cpp/iterator/istreambuf iterator">std::istreambuf_iterator</a></span> must have a trivial copy constructor, a constexpr default constructor, and a trivial destructor.
</li></ul>
</td>
<td><span class="t-mark-rev t-since-cxx11">(since C++11)</span></td></tr>
</table>
 <table class="t-rev-begin">
<tr class="t-rev t-until-cxx17"><td>
<ul><li> <span class="t-lc"><a href="../utility/functional/unary_function.html" title="cpp/utility/functional/unary function">std::unary_function</a></span> and <span class="t-lc"><a href="../utility/functional/binary_function.html" title="cpp/utility/functional/binary function">std::binary_function</a></span> may not be specialized.
</li></ul>
</td>
<td><span class="t-mark-rev t-until-cxx17">(until C++17)</span></td></tr>
</table>
<p>It is undefined behavior to declare a full or partial specialization of any member class template of a standard library class or class template.
</p>
<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style=""><tr><td class="mbox-empty-cell"></td><td class="mbox-text" style="">This section is incomplete<br>Reason: mini-example </td></tr></table>
<h4><span class="mw-headline" id="Function_templates_and_member_functions_of_templates">Function templates and member functions of templates</span></h4>
 <table class="t-rev-begin">
<tr class="t-rev t-until-cxx20"><td>
<p>It is allowed to add template specializations for any standard library function template to the namespace <code>std</code> only if the declaration depends on at least one program-defined type and the specialization satisfies all requirements for the original template, except where such specializations are prohibited.
</p>
</td>
<td><span class="t-mark-rev t-until-cxx20">(until C++20)</span></td></tr>
<tr class="t-rev t-since-cxx20"><td>
<p>It is undefined behavior to declare a full specialization of any standard library function template.
</p>
</td>
<td><span class="t-mark-rev t-since-cxx20">(since C++20)</span></td></tr>
</table>
<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style=""><tr><td class="mbox-empty-cell"></td><td class="mbox-text" style="">This section is incomplete<br>Reason: mini-example </td></tr></table>
<p>It is undefined behavior to declare a full specialization of any member function of a standard library class template:
</p>
<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style=""><tr><td class="mbox-empty-cell"></td><td class="mbox-text" style="">This section is incomplete<br>Reason: mini-example </td></tr></table>
<p>It is undefined behavior to declare a full specialization of any member function template of a standard library class or class template:
</p>
<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style=""><tr><td class="mbox-empty-cell"></td><td class="mbox-text" style="">This section is incomplete<br>Reason: mini-example </td></tr></table>
<h4><span class="mw-headline" id="Variable_templates">Variable templates</span></h4>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx14"><td>
<p>It is undefined behavior to declare a full or partial specialization of any standard library variable template, except where explicitly allowed. 
</p>
<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style=""><tr><td class="mbox-empty-cell"></td><td class="mbox-text" style="">This section is incomplete<br>Reason: mini-example </td></tr></table>
</td>
<td><span class="t-mark-rev t-since-cxx14">(since C++14)</span></td></tr>
</table>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx20"><td>
<ul><li> Specializations of <span class="t-lc"><a href="../iterator/sized_sentinel_for.html" title="cpp/iterator/sized sentinel for">std::disable_sized_sentinel_for</a></span>, <span class="t-lc"><a href="../ranges/sized_range.html" title="cpp/ranges/sized range">std::ranges::disable_sized_range</a></span>, <span class="t-lc"><a href="../ranges/view.html" title="cpp/ranges/view">std::ranges::enable_view</a></span> and <span class="t-lc"><a href="../ranges/borrowed_range.html" title="cpp/ranges/borrowed range">std::ranges::enable_borrowed_range</a></span> shall be usable in constant expressions and have type <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> <span class="kw4">bool</span></span></span>. And
<ul><li> <code>std::disable_sized_sentinel_for</code> may be specialized for cv-unqualified non-array object types <code>S</code> and <code>I</code> at least one of which is a program-defined type.
</li><li> <code>std::ranges::disable_sized_range</code>, <code>std::ranges::enable_view</code> and <code>std::ranges::enable_borrowed_range</code> may be specialized for cv-unqualified program-defined types.
</li></ul>
</li><li> Every <a href="../numeric/constants.html" title="cpp/numeric/constants">mathematical constant variable template</a> may be partially or explicitly specialized, provided that the specialization depends on a program-defined type.
</li></ul>
</td>
<td><span class="t-mark-rev t-since-cxx20">(since C++20)</span></td></tr>
</table>
<h3><span class="mw-headline" id="Explicit_instantiation_of_templates">Explicit instantiation of templates</span></h3>
<p>It is allowed to explicitly instantiate a <span class="t-rev-inl t-since-cxx20"><span>class </span> <span><span class="t-mark-rev t-since-cxx20">(since C++20)</span></span></span>template defined in the standard library only if the declaration depends on the name of at least one program-defined type and the instantiation meets the standard library requirements for the original template.
</p>
<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style=""><tr><td class="mbox-empty-cell"></td><td class="mbox-text" style="">This section is incomplete<br>Reason: mini-example </td></tr></table>
<h3><span class="mw-headline" id="Program-defined_types">Program-defined types</span></h3>
<p><i>Program-defined specializations</i> are explicit template specializations or partial specializations that are not part of the C++ standard library and not defined by the implementation.
</p><p><i>Program-defined types</i> are non-closure <a href="class.html" title="cpp/language/class">class types</a> or <a href="enum_class.html" title="cpp/language/enum">enumeration types</a> that are not part of the C++ standard library and not defined by the implementation<span class="t-rev-inl t-since-cxx11"><span>, or <a href="lambda.html" title="cpp/language/lambda">closure type</a> of non-implementation-provided lambda expressions</span> <span><span class="t-mark-rev t-since-cxx11">(since C++11)</span></span></span>, or instantiation of program-defined specializations.
</p>
<h3><span class="mw-headline" id="Other_restrictions">Other restrictions</span></h3>
<p>The namespace <code>std</code> may not be declared as an <a href="namespace.html#Inline_namespaces" title="cpp/language/namespace">inline namespace</a>.
</p>
 <table class="t-rev-begin">
<tr class="t-rev t-since-cxx20"><td>
<h4> <span class="mw-headline" id="Addressing_restriction">Addressing restriction</span></h4>
<p>The behavior of a C++ program is unspecified (possibly ill-formed) if it explicitly or implicitly attempts to form a pointer, reference (for free functions and static member functions) or pointer-to-member (for non-static member functions) to a standard library function or an instantiation of a standard library function template, unless it is designated an <i>addressable function</i> (see below).
</p><p>Following code was well-defined in C++17, but leads to unspecified behaviors and possibly fails to compile since C++20:
</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="cpp source-cpp"><pre class="de1"><span class="co2">#include &lt;cmath&gt;</span>
<span class="co2">#include &lt;memory&gt;</span>
 
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
    <span class="kw4">auto</span> fptr0 <span class="sy1">=</span> <span class="sy3">&amp;</span><a href="../numeric/special_functions/beta.html"><span class="kw1397">std::<span class="me2">betaf</span></span></a><span class="sy4">;</span> <span class="co1">// by unary operator&amp;</span>
    <span class="kw4">auto</span> fptr1 <span class="sy1">=</span> <a href="../memory/addressof.html"><span class="kw758">std::<span class="me2">addressof</span></span></a><span class="br0">(</span><a href="../numeric/special_functions/beta.html"><span class="kw1398">std::<span class="me2">betal</span></span></a><span class="br0">)</span> <span class="co1">// by std::addressof</span>
    <span class="kw4">auto</span> fptr2 <span class="sy1">=</span> <a href="../numeric/special_functions/riemann_zeta.html"><span class="kw1442">std::<span class="me2">riemann_zetaf</span></span></a><span class="sy4">;</span> <span class="co1">// by function-to-pointer implicit conversion</span>
    <span class="kw4">auto</span> <span class="sy3">&amp;</span>fref <span class="sy1">=</span> <a href="../numeric/special_functions/riemann_zeta.html"><span class="kw1443">std::<span class="me2">riemann_zetal</span></span></a><span class="sy4">;</span> <span class="co1">// forming a reference</span>
<span class="br0">}</span></pre></div></div>
<h4> <span class="mw-headline" id="Designated_addressable_functions">Designated addressable functions</span></h4>
<ul><li> <a href="../io/manip.html" title="cpp/io/manip">I/O manipulators</a>:
<ul><li> <code>fmtflags</code> manipulators:
<ul><li> <span class="t-lc"><a href="../io/manip/boolalpha.html" title="cpp/io/manip/boolalpha">std::boolalpha</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/boolalpha.html" title="cpp/io/manip/boolalpha">std::noboolalpha</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/showbase.html" title="cpp/io/manip/showbase">std::showbase</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/showbase.html" title="cpp/io/manip/showbase">std::noshowbase</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/showpoint.html" title="cpp/io/manip/showpoint">std::showpoint</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/showpoint.html" title="cpp/io/manip/showpoint">std::noshowpoint</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/showpos.html" title="cpp/io/manip/showpos">std::showpos</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/showpos.html" title="cpp/io/manip/showpos">std::noshowpos</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/skipws.html" title="cpp/io/manip/skipws">std::skipws</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/skipws.html" title="cpp/io/manip/skipws">std::noskipws</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/uppercase.html" title="cpp/io/manip/uppercase">std::uppercase</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/uppercase.html" title="cpp/io/manip/uppercase">std::nouppercase</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/unitbuf.html" title="cpp/io/manip/unitbuf">std::unitbuf</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/unitbuf.html" title="cpp/io/manip/unitbuf">std::nounitbuf</a></span>
</li></ul>
</li><li> <code>adjustfield</code> manipulators:
<ul><li> <span class="t-lc"><a href="../io/manip/left.html" title="cpp/io/manip/left">std::internal</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/left.html" title="cpp/io/manip/left">std::left</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/left.html" title="cpp/io/manip/left">std::right</a></span>
</li></ul>
</li><li> <code>basefield</code> manipulators:
<ul><li> <span class="t-lc"><a href="../io/manip/hex.html" title="cpp/io/manip/hex">std::dec</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/hex.html" title="cpp/io/manip/hex">std::hex</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/hex.html" title="cpp/io/manip/hex">std::oct</a></span>
</li></ul>
</li><li> <code>floatfield</code> manipulators:
<ul><li> <span class="t-lc"><a href="../io/manip/fixed.html" title="cpp/io/manip/fixed">std::fixed</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/fixed.html" title="cpp/io/manip/fixed">std::scientific</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/fixed.html" title="cpp/io/manip/fixed">std::hexfloat</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/fixed.html" title="cpp/io/manip/fixed">std::defaultfloat</a></span>
</li></ul>
</li><li> <code>basic_istream</code> manipulators:
<ul><li> <span class="t-lc"><a href="../io/manip/ws.html" title="cpp/io/manip/ws">std::ws</a></span>
</li></ul>
</li><li> <code>basic_ostream</code> manipulators:
<ul><li> <span class="t-lc"><a href="../io/manip/endl.html" title="cpp/io/manip/endl">std::endl</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/ends.html" title="cpp/io/manip/ends">std::ends</a></span>
</li><li> <span class="t-lc"><a href="../io/manip/flush.html" title="cpp/io/manip/flush">std::flush</a></span>
</li><li> <a href="../io/manip/emit_on_flush.html" title="cpp/io/manip/emit on flush"><tt>std::emit_on_flush</tt></a>
</li><li> <a href="../io/manip/emit_on_flush.html" title="cpp/io/manip/emit on flush"><tt>std::noemit_on_flush</tt></a>
</li><li> <a href="../io/manip/flush_emit.html" title="cpp/io/manip/flush emit"><tt>std::flush_emit</tt></a>
</li></ul>
</li></ul>
</li></ul>
</td>
<td><span class="t-mark-rev t-since-cxx20">(since C++20)</span></td></tr>
</table>

<!-- 
NewPP limit report
Preprocessor visited node count: 4817/1000000
Preprocessor generated node count: 11435/1000000
Post‐expand include size: 142399/2097152 bytes
Template argument size: 29670/2097152 bytes
Highest expansion depth: 20/40
Expensive parser function count: 0/100
-->

<!-- Saved in parser cache with key mwiki1-mwiki_en_:pcache:idhash:13097-0!*!0!!en!*!* and timestamp 20220627192645 -->
</div>                    <!-- /bodycontent -->
                                        <!-- printfooter -->
                    <div class="printfooter">
                    Retrieved from "<a href="https://en.cppreference.com/mwiki/index.php?title=cpp/language/extending_std&amp;oldid=136879">https://en.cppreference.com/mwiki/index.php?title=cpp/language/extending_std&amp;oldid=136879</a>"                    </div>
                    <!-- /printfooter -->
                                                            <!-- catlinks -->
                    <!-- /catlinks -->
                                                            <div class="visualClear"></div>
                    <!-- debughtml -->
                                        <!-- /debughtml -->
                </div>
                <!-- /bodyContent -->
            </div>
        </div>
        <!-- /content -->
        <!-- footer -->
        <div id="cpp-footer-base" class="noprint">
            <div id="footer">
                        <div id="cpp-navigation">
            <h5>Navigation</h5>
            <ul><li><a href="https://en.cppreference.com/w/cpp/language/extending_std">Online version</a></li><li>Offline version retrieved 2022-07-30 14:05.</li></ul></div>
                        <ul id="footer-info">
                                    <li id="footer-info-lastmod"> This page was last modified on 3 January 2022, at 23:35.</li>
                                    <li id="footer-info-viewcount">This page has been accessed 88,585 times.</li>
                            </ul>
                    </div>
        </div>
        <!-- /footer -->
        <script>if(window.mw){
mw.loader.state({"site":"loading","user":"missing","user.groups":"ready"});
}</script>
<script src="../../../common/skin_scripts.js"></script>
<script>if(window.mw){
mw.loader.load(["mediawiki.action.view.postEdit","mediawiki.user","mediawiki.page.ready","mediawiki.searchSuggest","mediawiki.hidpi","ext.gadget.ColiruCompiler","ext.gadget.MathJax"], null, true);
}</script>
<script src="../../../common/site_scripts.js"></script>
<script type="text/javascript">
var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-2828341-1']);
_gaq.push(['_setDomainName', 'cppreference.com']);
_gaq.push(['_trackPageview']);
</script><!-- Served in 1.273 secs. -->
	</body>
<!-- Cached 20220627192645 -->
</html>